Oxygen is produced commercially in large quantities by the cryogenic rectification of feed air, generally employing a double column system wherein product oxygen is taken from a lower pressure column. At times it may be desirable to produce oxygen at a pressure which exceeds its pressure when taken from the lower pressure column. In such instances, gaseous oxygen may be compressed to the desired pressure. However, it is generally preferable for capital cost purposes to remove oxygen as liquid from the lower pressure column, increase its pressure, and then vaporize the pressurized liquid oxygen to produce the desired elevated pressure product oxygen gas.
It is desirable in such a system to produce the elevated pressure oxygen product as efficiently as possible. Accordingly, it is an object of this invention to provide a cryogenic air separation system which can produce elevated pressure oxygen with improved efficiency and lower cost than heretofore available cryogenic air separation systems for producing such elevated pressure oxygen.